Pioneer TS-W3002D2 Champion Series Pro 12" sub with dual 2-ohm voice coils at Crutchfield
TS-W310S4 - Pioneer 12" 400W RMS Single 4-Ohm Champion Series Subwoofer
Amazon.com: Pioneer TS-A300D4 12 Inch 1500 Watts Max Power Dual 4-Ohm Voice Coil A Series Car Audio Stereo Subwoofer Loudspeakers / Free Alphasonik Earbuds : Electronics